The following U.S. patents are incorporated herein by reference, in entirety:
U.S. Pat. No. 4,573,318 discloses a marine propulsion system provided with an exhaust elbow having an intake exhaust passage extending upwardly from the engine and communicating through a bend with a discharge exhaust passage. A cooling jacket has pockets around the exhaust passages for cooling the latter. A central channel extends longitudinally along the exterior of the exhaust passages to guide water to the end of the discharge exhaust passage to mix with exhaust. The central channel has a pair of sidewalls extending longitudinally and laterally tapered away from each other at the outer end of the discharge exhaust passage to create an outward draw from the central channel to minimize break-up of longitudinally outward water flow and maintain the end tip of the discharge exhaust passage dry and prevent water ingestion and creeping back into the discharge exhaust passage due to pulsations of the engine. Dam and port structure is also provided enabling faster heating of the exhaust passage and in turn minimizing condensation within the elbow which may otherwise ingest back into the engine.
U.S. Pat. No. 8,403,717 discloses a marine propulsion system having an exhaust conduit that conveys exhaust gases from an internal combustion engine. The exhaust conduit has a dry portion and a wet portion located downstream of the dry portion. Cooling fluid enters the exhaust conduit to cool exhaust gases flowing through the wet portion. A bypass conduit is connected to the exhaust conduit and conveys a portion of the cooling fluid away from the dry portion to thereby decrease reversion of cooling fluid into the dry portion.
U.S. Pat. No. 8,899,029 discloses apparatuses for marine propulsion systems having an internal combustion engine. The apparatuses comprise an exhaust conduit conveying exhaust from the internal combustion engine; a cooling jacket on the exhaust conduit; and a cooling passage between the exhaust conduit and the cooling jacket. The cooling passage guides flow of cooling liquid from upstream to downstream towards a location where the cooling liquid is mixed with exhaust in the exhaust conduit. First and second baffles are axially spaced apart and extend transversely with respect to the cooling passage so as to disperse the flow of cooling liquid at the location where the cooling liquid is mixed with the exhaust, thereby reducing reversion of cooling liquid in the exhaust conduit. At least one catalyst and at least one oxygen sensor are disposed in the exhaust conduit. The oxygen sensor is adjacent to and oriented parallel to a downstream face of the catalyst so that exhaust flows perpendicularly across the sensor.